The present invention is directed to a planar member as well as associated arrangements for mounting of the member in a machine for cutting sheet elements, such as for example sheets of paper or cardboard, or in an annexed control table. The invention concerns more particularly a member for supporting equipment for ejecting waste which member is installed in an ejection or stripping station, or a member having cutters which member is installed in a cutting platen press.
At present, machines are used to cut one or more box blanks into a sheet of material which blanks after folding and gluing, may be formed into boxes. Each blank has a format that generally includes six surfaces of a box with certain edges being provided with tongues or flaps for gluing and closing. Advantageously, the waste, which is the unused area of the sheet between the tongues or between the different blanks, is immediately ejected after cutting, so that in the output stack only sheets which contain finished blanks interconnected by break points are collected or accumulated.
A machine of this type usually comprises an input station in which the sheets are taken one by one from the top of a stack in order to be sent to a feed table where they are placed in position against front and lateral stops. The sheet can then be grasped at a front edge by a series of grippers or clamps mounted along a transverse bar whose ends are attached to lateral chain trains of a chain conveyor for leading the bar and any attached sheet into subsequent processing stations. The sheet is then conveyed into a cutting station comprising a platen press provided with cutters, which press is actuated during a dwell in the movement of the chain to cut the various blanks into the sheet. From the cutting station, the sheet is then conveyed to an ejection or stripping station where the waste material is grasped by pins in order to be moved downward into a container. If desired, the cutting station may be preceded by a printing station, also with platen. These processing stations are followed by a receiving or delivery station in which each cut sheet is released from the grippers or clamps so as to fall squarely onto the top of an output stack of die cut and stripped sheets.
In the ejecting or stripping station, the sheet is led flatly onto a first median means in the form of a horizontal board which is provided with apertures according to the periphery of the areas to be stripped from the die cut sheet. An upper horizontal stripping means, bearing stripping or ejecting pins, ejectors or pressers, is movable in the vertical direction according to an alternating motion, synchronized so that the ejecting or stripping means is lowered shortly after the arrival of a sheet. Under the aperture board is located a second horizontal ejecting or stripping means, called the lower means, which has vertical telescopic pins arranged in correspondence with the upper ejectors. Thus, when the upper stripping means lowers itself onto the cut sheet placed in position on the board, the respective combination of the ejector pins of the upper means and the telescopic pins grasp the waste areas and hold them as they move them downward, where they fall into the container.
In the following, the terms upstream and downstream are used in reference to the direction of displacement of the sheets, so that a piece on the upstream side is close to the entrance to the station, while a piece on the downstream side is close to the exit. Analogously, the expressions left and right are to be understood in relation to the running direction of the strip, with the left side usually being the driving side or the operator side and the right side being the side opposed to the driving side of the machine.
The ejecting or stripping means is changed for every change of production series in order to adapt the stripping means to new demands such as the type of sheet, the sheet format, and the various contours of the parts to be ejected or stripped from die cut sheet. In particular, the lower means must be designed so that its structure does not interfere with the free falling of the waste materials, once these have been removed from the die cut sheet.
To accomplish these goals, the upper and lower stripping means currently in use are each made up of immovable metallic rectangular interior frames to which a grid of crossbeams is attached. This frame and these crossbeams are made of formed metal bars, which are preferably made of aluminum, so as to be relatively light and save weight. The fact that these bars are shaped so as to be higher than they are wide ensures a great rigidity in the vertical direction of the stripping means. The ejecting or stripping means properly so called are then arranged along the crossbeams as needed and are held there by anchoring pieces.
The exterior surfaces of the upstream and downstream crossbeams of the frame of the stripping means comprise a groove that enables the means to be removed and then reinstalled in the station by passing through a lateral window or port and sliding it along the two upstream and downstream strips belonging to the drive mechanism of the stripping station. In addition, the frame is provided in its four corners with centering posts that have conical parts and that receive the locking tenons.
In order to facilitate the modification of these stripping means during changing from one production series to another, the stripping means are removed from the station and installed in a control table, i.e. a structure comprising pairs of support strips for the stripping means, arranged one above the other, and locking arrangements for the centering posts. In this table, the order of the stripping pins is inverted with the upper stripping means being installed in the lower part of the table, and the lower stripping means being installed in the upper part. This arrangement facilitates the precise positioning of the telescopic pins of the lower stripping means opposite the ejectors of the upper stripping means.
The handling of these ejecting or stripping means from the station to the control table and then back again is long and tiresome, due to the weight and cumbersomeness of these stripping means. Certain shops are equipped with lifting devices whose hook is specially adapted to lift an ejecting or stripping means and move it horizontally. Other shops have means for lifting the entire control table in order to lead it directly against the window or port of the station in order to slide the stripping means only. However, these operations are still very delicate.
Moreover, since the upper stripping means does not require intermediate space for the passage of the waste, the idea occurred to replace the grid of internal crossbeams with a single board in which are implanted the ejecting pins, ejectors and pressers. However, the holding of this board in the frame by means of a plurality of screws distributed on the periphery of the frame and supported against the edge of the board too frequently caused a warping of the board, which would distort the alignment of the pins. In addition, it was necessary to attach a rigid plate against an upper surface in order to hold the reaction forces to the pushing of the waste down and this caused the stripping board to remain too heavy and cumbersome.